Press polymerization of lenticular images

ABSTRACT

Methods and apparatus for producing autostereograms using ultraviolet radiation-curable thermosetting polymers. A stereoscopic image is printed upon a plastic or paper sheet, which is fed directly onto a surface having an inverse lenticular pattern relief. As the sheet is fed onto the surface, a flow of ultraviolet-curable thermosetting polymer resin is directed at the surface. Ultraviolet radiation is directed at the polymer layer, curing the polymer and forming a lenticular array on the front surface of the polymer layer. During this process, the sheet carrying the stereoscopic image is bonded to the back surface of the polymer lenticular layer in precise registration with the lenticular array. In a preferred embodiment of the invention, the inverse lenticular pattern relief is on the outer surface of a transparent cylinder. The polymer layer is cured as it is flowed onto the relief pattern by an ultraviolet lamp placed within the transparent cylinder.

BACKGROUND

1. Field of the Invention

The present invention relates to autostereoscopic and related imagesproduced by concurrently printing images on paper or plastic andfabricating a lenticular polymer lens surface, The lenticular pattern isproduced by applying a reactive polymer layer to the outer surface of atransparent cylinder having a lenticular pattern in relief on its outersurface and casting the pattern in registration with the image usingradiation from an ultraviolet light source.

2. Background of the Invention

Autostereoscopic imaging is a technique for providing three-dimensionalimages. Autostereoscopic imaging is described in U.S. Pat. No. 5,113,213to Sandor et al. This patent describes a method and apparatus for makingautostereographic images by interleaving a number of images in acomputer and printing the interleaved images on a printer. Thespecification, and drawings of this patent are incorporated herein byreference.

DEPTH PERCEPTION

Stereo vision results principally from three depth cues: binocularparallax, monocular movement parallax, and psychological factors.Binocular parallax is due to the spacing between the observer's left andright eyes. Because of the distance between the eyes, light rays from agiven object enter the left eye at a slightly different angle than lightrays from the same object enter the right eye. The brain integrates thetwo physical images received by the eyes into one perceived image. Thebrain deduces the distance to the object from the difference in theangles. The threshold distance for the minimum perception of binocularparallax is approximately 10 inches.

Monocular movement parallax arises from the shift in the image of anobject as the angle from which that object is viewed changes. Monocularmovement parallax can be perceived even from a single eye, as long asthat eye is moving. The more rapidly the eye moves, the more acute themonocular movement depth perception becomes.

Psychological factors such as size, haze, and gradients in shading,shadows and texture also contribute to depth perception. We know theactual size of most objects from experience and memory. As an objectrecedes in the distance, the size of its image on an observer's retinabecomes smaller. Therefore, the size of the image of a familiar objecton the observer's retina is inversely related to the distance to theobject. In still photography this principle can be employed to trick theviewer into believing that greater than actual depth is being perceivedby reducing the size of background objects in the photograph.

The psychology of depth perception dates back to 280 A.D. when Eucliddefined binocular parallax as the means by which each eye receives thesimultaneous impression of two dissimilar images of the same object.This basic principle is applied today in methods of autostereographyusing lenticulated lens sheets or barrier strip systems which providethe optics necessary for the perception of depth, without the need forthe observer to wear filters or glasses°

BACKGROUND OF 3-D IMAGES

With the invention of photography, it was discovered that twophotographs of the same object taken from slightly different viewpoints,if presented to each eye as independent images, would produce athree-dimensional image. Several inventors in the 1800s developed handheld stereoscopes.

To present three-dimensional images to a large audience, a pair ofstereoscopic images would be projected in two separate colors and viewedwith glasses having complementary color filters over each eye. Thisanaglyphic method for viewing three-dimensional images with glasses wasalso used for early three-dimensional motion pictures and for printedimages when filtered glasses could be provided. The common colors usedfor images and filters were red and blue or red and green: the redfilter neutralizes the red images and the blue or green filterneutralizes the blue or green image. This approach could not be used forfull color images.

When color film became available for motion pictures, the left and rightimages could no longer be separated using color filters. Polarizationfilters were developed to replace the color filters. However, polarizedfilters cannot be used for three-dimensional television, because thetelevision screen cannot display polarized images. The most successfulsystems developed for three-dimensional television separate the imagesin time, instead of by polarization. These systems use a liquid crystalshutter on the televised image synchronized with shutters on the leftand right eyes. However, this system requires the observer to wearliquid crystal shutters over the eyes synchronized with the left andright eye views of the CRT images.

The color, polarizer and shutter stereoscopic systems described aboveare not autostereographic systems because the observer must wear anoptical devices such as eyeglasses having color filters, polarizers, orelectronic shutters to perceive the three-dimensional image.

AUTOSTEREOGRAPHY

Autostereography was invented in 1908 by M. G. Lippman. Lippmandeveloped the fly's-eye lens lenticular sheet. The lens sheet containedthousands of small convex lenses arranged either in a random or in anoriented array pattern. A photographic plate placed at the focal planeof the lenses was exposed through a large diameter lens to lightreflected from an object. The film recorded the thousands of smallphotographs as a large integral photograph. A three-dimensional imagecould be perceived from any angle when a positive of the integralphotograph was placed in exactly the same position relative to theconvex lens array as the photographic plate. A second kind ofautostereogram was developed to make the registration process lessdemanding. The arrays of convex lenses were replaced with planar arraysof cylindrical lenses. The cylindrical lenses preserved only thehorizontal parallax information--the vertical parallax information waslost. Such an image could be viewed from left to right, but not up anddown. This approach made registration easier, since only horizontalregistration was required.

The lenses in the lenticular sheet were separated from the image by theremaining thickness of the lenticular sheet such that the lenses wouldfocus on the image at the rear surface of the material. A photographicemulsion was placed against the rear surface of the sheet, and anexposure was made through the lenticular sheet. The image plane wasmoved horizontally during the exposure, resulting in fine columns ofleft and right eye images. This structure is perceived as athree-dimensional image when viewed through a lenticular screen.

Barrier strip stereograms are a third kind of autostereogram. In barrierstrip autostereograms, images are viewed through fine transparentvertical slits in an opaque surface. Parallax factors affect barrierstrip three-dimensional images in the same manner as lenticular lenssheets. Barrier strip stereograms must be illuminated from the rear,since ambient room light will not effectively illuminate the image fromthe front. The much brighter illumination is necessary because only10-20% of the barrier strip is transparent--the remaining 80-90% isopaque.

Lenticular screen systems thus have an advantage over barrier stripsystems, in that images in lenticular systems can be viewed in eitherthe reflection or the transmission modes.

MANUFACTURE OF LENTICULAR SHEETS

The manufacture of lenticular sheets requires engraving a master reliefpattern from which replications could be made. A number of conventionalmanufacturing methods have been adapted to produce lenticular sheetswith the desired optical characteristics. These manufacturing methodsinclude tooling, platen press, injection or compression molding,embossment, extrusion, and casting. The materials used include a varietyof clear optical materials including glass and many types of plastics.Each of these prior art methods suffer inherent problems which renderthem ineffective for the high-volume production of lenticular screensfor autostereography.

Machining can be used to directly manufacture coarse, one-of-a-kindlarge lenticular screens in thick plastic sheets. Milling machines orlathes can be used with a diamond tip tool having a pre-determinedradius. However, machining is a slow and costly process. This method formanufacturing lenticular screens is not well-suited to volumeproduction.

A platen press can be used to stamp or emboss an engraved relief patterninto a thermoset material. The temperature of the thermoset material israised to soften the material so that it conforms to the engravedsurface. The temperature of the material is reduced to harden thematerial such that it retains the relief pattern when removed from theplaten press. Like machining, this method is slow and expensive.Furthermore, the sheet size is limited. This method is not suited forhigh volume production or for producing a continuous length product.Similar problems apply to injection or compression techniques formanufacturing molded lenticular screens.

The most common method for manufacturing high-volume lenticular sheetsis by extrusion embossment in continuous length roll form. Typically,these systems utilize an engraved roller with a thread-like screw pitchto the relief pattern. The quality and definition of extrusion reliefpatterns are generally inferior to patterns obtainable by platen orultra-violet casting methods.

Extrusion techniques have difficulty maintaining the absoluteparallelism of the lenticular rows. Because of the elastic nature of themolten plastic material and the internal stresses imparted by theembossing roller, the sheet has a tendency to change from its impressedshape prior to being fully set. Additionally, extrusion lenticularsheets can streak due to condensation, adding to the dimensionaldistortion and migration of the lenticular surface. These physicaldistortions optical defects in the lenticular sheet result in seriousdistortions and degradations in the perceived image. Migration is thetendency of the extruded plastic to move in a direction perpendicular tothe direction of lenticulation during the extrusion process.

The optical quality of extruded lenticular sheets also suffers from theinfluences of the polymers from which they are formed. Some extrusionsystems attempt to control this problem by curtain coating the polymersto a pre-extruded non-lenticulated web sheet requiring a binder coatingto produce the multi-layered ply-sheet. Curtain coating is a process inwhich a flow of liquid plastic is set by a chill roller. This does notcontrol the migration problem and adds defects such as bubbles,separation of surfaces, and diffusion of images, thus reducing theoptical quality of the lenticular sheet.

These problems were addressed by a photographic technique using athermoset UV casted sheet developed in the 1980s. The technique used acomposite sheet having a back surface coated with a photosensitiveemulsion. The stereoscopic images were obtained as multiple exposures ofthe photosensitive emulsion through a lenticular screen. The compositesheet had a layer of cured thermosetting polymer on one surface of abase polymer film. The patterned lenticular relief was imposed upon thethermoset layer by curing the thermosetting resin while it is wrappedaround a molding surface. The technique requires that it be used onlywith continuous roll transparent films. The disadvantage of thisapproach is that only special dedicated equipment could produce overallfull-width lenticulated continuous roll transparent films.

The needs for printing applications are very different. Lenticulation isonly required in the three-dimensional picture area of a sheet or pageof a book, and not on the entire surface. When the lenticulation coversan area of text, the text becomes much harder to read. Additionally,fully lenticulated pages add an unnecessary cost to the finishedproduct.

GEOMETRY OF THE LENTICULAR SHEET

The geometry of the lenticular sheet is determined by the conditionsunder which the image is obtained. To create autostereographic images,the object is photographed at two slightly different viewing angles,simulating the parallax created by the average 6.5 cm separation of twoeyes. The difference in the viewing angles is determined by the distancefrom which the autostereoscopic display is to be viewed (the "viewingdistance").

As the viewing distance increases, the pitch of the lenticular sheetbecomes increasingly coarse and the thickness of the sheet increases inorder to retain focus as the lens radius increases with pitch. The pitchis the number of lines per inch of the image. The format size of theimage also generally increases with the viewing distance. Smallhand-held lenticular sheet autostereographs require a very fine pitch,e.g., from 80 to 300 lines per inch. Larger lenticular screenautostereographs can have a pitch with as few as 10 to 40 lines perinch. As the cylindrical lenticules become smaller, in finer pitchlenticular screens, the thickness of the lenticular sheet is alsoreduced so that the lenticules can focus upon the back surface of thescreen.

To produce high quality autostereographs, the lenticular sheet itselfmust have good depth resolution. Assume that the thickness of thelenticular sheet selected will allow a bundle of parallel incident beamsof light to focus on the back surface of the sheet. The light beams thusform a single spot so that an observer cannot distinguish more than onespot inside any cylindrical lenticule from a given position. The widthof the lenticule determines the minimum resolvable lateral pictureelement.

When lenticular screens are used with pre-established image pitches,such as in photo duplication or in printed images, the lenticules mustbe consistently and reliably identical and parallel, in order toregister to the pre-established image. Lens aberrations, or variationsin the thickness of the spacer sheet, may misdirect the outgoing beams,so that the perceived image is other than the defined image at a givenviewing angle. However, when the lenticular screen is used with aphotosensitive emulsion applied to the back side of the lens, andprojections of the stereo images are made through the lens, most of thedistortion due to migration or non-parallelism is self-cancelling.

Except for extreme variations, these distortions do not effect thephoto-composed (one-of-a-kind) three-dimensional images. However,dedicated three-dimensional photography, photo-mechanical combinationsor graphic arts separation and scanner-generated lenticular patternsrequire a standard pitch. The display lenticular screens must be made toconform exactly to the pitch and parallelism of the lenticular systemused to generate the original image. Correction must also be made forthe parallax angle when determining the pitch of the lenticular screen.

SUMMARY OF THE INVENTION

The present invention is an apparatus and method for the fabrication oflenticular sheets for use in autostereography.

In a first preferred embodiment of the present invention, the reliefpattern is formed as an array of inverse lenticules around a quartzglass or other transparent type of cylinder. An ultraviolet (UV) lamp isplaced at the center of the cylinder. The substrate for the lenticularscreen is wrapped partially around the cylinder as a flow of UV-curablepolymer is directed between the substrate and the cylinder. Air must beprevented from reaching the polymer because oxygen would inhibit thecuring of the polymer. A typical polymer used in this apparatus can becured at rates of 100 to 150 feet per minute with exposure to 200 to 400watts of UV radiation per inch. A continuous web of substrate is fedaround and onto the cylinder. The lenticular pattern is printed in-linejust prior to the formation of the lenslets in the polymer over theprinted image. A register line is printed at the edge of the substratein alignment with the image and read by a sensor that adjusts theleft-right movement of the cylinder to maintain registration of thelenticular pattern to that of the pre-printed image.

In the first preferred embodiment of the invention, the thermosettingpolymer layer is an actively curable resin, which is cured and hardenedby exposing the uncured thermosetting composition to active radiationwhile leaving the cast of the molding plate and impression cylinder of aweb printing press. Furthermore, full curing of the sheet isaccomplished in-line with the image printing. The resin only requires UVradiation for curing. Heating or chilling may be applied to control theviscosity of the polymer.

The lenticular sheets may be produced in continuous rolls or inindividual sheets using a press slitter. The lenticular surface isapplied to images being printed in-line in a single operation. Thissingle-step procedure eliminates the need for adhesives and preciseregistration of the image and the screen, as required by the prior art.Furthermore, the invention can be practiced using existing offsetprinting equipment, a source of ultraviolet radiation, and specialrelief-patterned cylinders.

The relief pattern plate is formed with a pitch (i.e., lines per inch)that is compatible with the pitch of available graphic arts outputdevices such as laser scanners. The pitch of the plate is determinedaccording to the following formula:

    PITCH.sub.plate =(PITCH.sub.scanner)/(number of images)

Because the pitch of the lenticular pattern is compatible with theoutput of the scanner, computer generated images are produced in exactregistration with the lenticular screen.

The lens thickness and the lens curvature required to produce the properfocal length and sharpness of the image determine the correct pitch.Typically, printing presses are made to accept substrates approximately20 mils thick. This leaves a wide range of pitches available for boththick and thin substrates. When printing on paper, with an 8 to 10 milsthick polymer layer, a pitch of 150 to 250 lines per inch would requirea radius of from 2.67 mils to 3.33 mils with a depth of pattern lessthan 2 mils.

On plastic substrates, the pitch can be more coarse for a longer viewingdistance, because the substrate itself provides the majority of the lensfocal length. In this case, pitches as low as 80 lines per inch could beused with polymer overcoats less than 3 mils thick. The exact radius ofthe lens, thickness of the lenticular sheet and pitch of the lenticularpattern is determined by the refraction index of the polymer used(typical polymers used for the manufacture of lenticular sheets have anindex of refraction of approximately 1.558). The viewing angle of thelenticule must be 30° degrees or more for proper movement of objectsoff-axis to the center plane of the image without objectionable flicker,sinuosity or ghosting.

The master relief patterned plate is made using a cutting tool conformedto the desired radius of the lenticule. The cylinder is made as areplication of the end product with the radius tool indenting the lensedges into the surface rather than having the sharp edges protrudingfrom the surface. The circumference of the cylinder is equal to theheight of the image, and the width is equal to the width of the image.With a plastic substrate, a pitch of 162 lines per inch will yield alenticular screen which is 20 mils thick overall, each lenticule being6.1728 mils wide and having a radius of 6.67 mils. A base sheet 15 milsthick would require a cured thermosetting polymer layer 5 mils thickopposite to the image side. With a paper substrate, a polymer thicknessof 8 mils would require a radius of 2.67 mils at a pitch of 250 linesper inch. A compromise lenticular relief patterns that could be usedwith either paper or plastic substrates would have a pitch of 162 linesper inch, with the lenticles having a radius of 4.17 mils. This patternwould be used with a 10 mil thick base sheet for plastic substrates (fora total thickness of 12.5 mils), and a 12.5 mil thick base sheet forpaper substrates.

A further significant feature of the present invention is that iteliminates all secondary operations required by the prior art. Noadhesives, mounting, registration, or optical alignments are necessary.In a single operation, three-dimensional or multi-images can be printedon available substrates with the added lenticular layer being formedsubstantially bonded to the substrate as the layer is cast and cured inregistration with the images being printed.

It is an object of the present invention to provide a method andapparatus for concurrently printing stereographic images in-line withthe formation of a lenticular screen.

It is a another object of the present invention to eliminate distortionsin lenticular autostereographic displays.

It is a further object of the present invention to provideautostereographs that can be specifically tailored for use in printedmedia such as illustrated books.

These and other objects of the present invention are described ingreater detail in the detailed description of the invention, theappended drawings and the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a cross-section of one type oflenticular screen fabricated according to the present invention.

FIG. 2 is a schematic representation of a cross-section of a second typeof lenticular screen fabricated according to the present invention.

FIG. 3 is schematic representation of a cross-section of a third type oflenticular screen fabricated according to the present invention.

FIG. 4 is a schematic representation of a commercial web press coatingunit adapted to practice the present invention.

FIG. 5 is a schematic representation of a commercial tower coateradapted to practice the present invention.

FIG. 6a is a perspective view of a relief pattern being cut into aremovable copper sleeve.

FIG. 6b is a cross-sectional schematic of a master copper relief patternand a replicated "mother" pattern formed or cast in a polymer layerbonded to a polycarbonate base film.

FIG. 7a is a perspective view showing how flowable polymer resin isapplied according to one method of the present invention.

FIG. 7b is a cross-sectional schematic of the relief pattern forming thelenticules in the polymer resin.

FIG. 8 is an illustrated block diagram showing schematically the methodof the present invention used with paper substrates on a sheet-fed presswith conventional cylinders.

FIG. 9 is an illustrated block diagram showing schematically the methodof the present invention used with plastic substrates on a sheet-fedpress with a transparent cylinder containing a UV light source.

FIG. 10 is an illustrated block diagram showing schematically the methodof the present invention used with plastic substrates on a web pressequipped with a transparent cylinder containing a UV light source.

FIG. 11 is a perspective view of a commercial tower coater adapted topractice the present invention.

FIG. 12 is a perspective view of a commercial web press coating unitadapted to practice the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 show two lenticular sheets manufactured according to thepresent invention. Both these lenticular sheets use an opaque paper orplastic layer to carry the image. These lenticular sheets must be usedin the reflection mode, i.e. the viewing light enters the lenticularsheet from the front surface, and is reflected back out by an opaqueimage-bearing layer. FIG. 1 is a cross-section of the lenticular sheet,showing thermosetting polymer layer 10, binder coating 13, basesubstrate 14 and lenticles 17. Base substrate 14 has substantiallysmooth front and rear planar surfaces. Binder coating 13, which isoptional, is a polymethyl acrylic such as National Chemical Company'sNICOAT coating.

In the lenticular sheets illustrated in FIGS. 1 and 2 a complementarylenticulated image is printed on the top surface of substrate 14. Thisprinted surface is positioned at the focal point of the lenticles 17formed on the top surface of polymer layer 10. In this embodiment theimage is printed on a paper layer or other opaque stock.

The lenticles 17 are elongated, parallel, rib-like cylindrical lenseshaving a narrow width and a uniform size and shape. The lenticles mayextend over all the surface as shown in FIG. 1, or over only part of thesurface as in FIG. 2. Each individual lenticule 17 in polymer layer 10defines an elongated substantially cylindrical lens having apredeterminedfocal length. The focal length of the lenticles is locatedat the rear surface of the polymer being cured, i.e., at layer 13 ofFIGS. 1 and 2.

The focal length is determined by the width and radius of curvature ofthe lenticles, and the index of refraction of the polymer layer. Theindex of refraction of the polymer layer is generally about 1.558.Typically, the width of each individual lenticule is 4-16 mils providing60 to 250 lines per inch. The thickness of the polymer layer dependsupon the radius of curvature of the lenticule and the index ofrefraction of the polymer. Thethickness typically ranges from 6 to 10mils. The polymer layer can be deposited onto the substrate in severallayers. For example, FIG. 2 shows a polymer layer formed by depositing afirst layer 11 over the entire surface of substrate 14 and then a secondlayer 12 over only part of the substrate. However, several layers may bedeposited sequentially over the entire substrate to build up the properfocal distance between the lenticles 17 and the image plane at 13.

FIG. 3 is a cross-section of a back-lighted transmission mode lenticularsheet. It differs from the reflection mode lenticular sheet of FIG. 1primarily by having a transparent plastic base film 15. The thickness ofplastic base layer 15 may range from 8 to 20 mils. For the particularend use applications illustrated herein, the thickness of the base filmis greater than the overall thickness of the thermosetting polymer layer19. A bonding coating 13 of polymethyl acrylic may be applied using aprior press unit if required.

The image 16 is printed on the back side of base layer 15 in four oreight colors, depending on the required saturation needed, with one ortwo layers of opaque white ink to act as a diffusion surface or to actas a white backing for reflected images. Thermosetting polymer layer 19is bonded to the top of base layer 15 using bonding coating 13. Baselayer 15is preferably a molecularly oriented thermoplastic polymerhaving good strength and dimensional stability such as the propertiesfound in polycarbonates.

Examples of materials suited for use as a base layer 15 includepolycarbonate (Lexan™ or Merlon™), and polyesters, such as polyethyleneterephthalate (e.g., Mylar™). This type of molecularly oriented film isused because of its excellent strength and dimensional stability as wellas its transparency, index of refraction and uniform overall thicknessor caliper. Additionally, it has been found that excellent bond strengthcan be achieved between the polycarbonate or polyester base layers 15and thermosetting polymer layer 19, especially when the surface iscoated with a bonding layer 13.

The method of making the lenticular relief pattern is shownschematically in FIG. 4 and in the perspective view FIG. 12. This methoduses a coating station unit typical of a narrow web printing press. Theflowable uncured thermosetting resin is pumped into a reservoir trough20 between the substrate layer 21 and relief pattern 22 on the surfaceof quartz glass cylinder 23. The resin flow is metered at the end ofsupply tube 24 to provide the proper amount of polymer resin, thusmaintaining constant coverage of the relief pattern 22. The proper flowrate depends upon the rate of operating speed at the press printstations.

The thermosetting polymer is thus transferred from trough 20 to reliefpattern 22 on the surface of transparent, e.g., quartz or glass,cylinder 23. The cavities of the inverse lenticular surface of reliefpattern 22 uniformly fill with the polymer resin while maintaining thedesired coating thickness. The resin 20 is formed into a lenticularpattern by thepressure between quartz glass cylinder 23 and substrate21. To provide the additional thickness of the polymer layer requiredfor proper focus, the pattern 22 on cylinder 23 retains a depth, inaddition to the cavities required to form the lenticules themselves,equal to the focal length of the lenticules. The polymer is then exposedto ultraviolet radiation emitted by UV lamp 31. The UV radiation curesthe polymer resin, so that it hardens and bonds to the substrate. UVlamp 31 is mounted within transparent cylinder 23 with gap 25 andreflector 26. Reflector 26 focusses the UV radiation onto the castingarea of relief pattern 22. Substrate 21 is then separated from reliefpattern 22 in exact registration with the printed image 23.

The thermosetting polymer layer can be applied to images printed onpaper (for reflection mode viewing as in FIG. 1) or to images printed onclear transparent plastic sheets (for transmission mode viewing as inFIG. 3, and as shown as printed areas 33 in FIGS. 4 and 12).

The resulting lenticular sheet has excellent dimensional stability andexcellent resistance to solvents, staining and heat. Furthermore, thelenticular formations are an exact reproduction of the molding surfaceandhave significantly better definition and lens like qualities thanlenticular formations produced in a thermoplastic extrusion process byconventional prior art thermal embossing techniques. The fine andaccuratedefinition of the lenticular formation is permanent and stableand does notchange with time or as a result of the application of heat,as in the lenticular formations which are formed in the extrusionprocess. Since theresin is cured in situ, there are no stresses impartedto the resin as in an embossing operation. The cured resin layer is thusessentially unstressed and has no molecular orientation. Lenticularthermolens sheets produced according to the present invention also avoidthe problems of pattern migration, watermarks and bubbles which occurduring cooling and condensation of heat-embossed lenticular screens.

FIG. 5 and the perspective view in FIG. 11 show the use of a towercoater in a first preferred embodiment of the present invention. Towercoaters are commonly used with newer offset lithographic printingpresses. Tower coaters provide "instant dry" in-line dispersion coatingsapplied on top of wet inks. Dual applications of an aqueous coatingfollowed by a UV overcoat for gloss or protection of the printed imageare often applied with interstation drying between units. Evaporation ofwater or solvents can be enhanced with infrared and hot-air dryers.

Coaters come in three varieties: dampener coaters, using a conventionalpress unit to track solid coating areas to the press blanket andsubsequently to the printed sheet as the last impression before drying,and in a perspective view (FIG. 11), tower coaters built into the pressasshown in FIG. 5, and retractable blanket or impression cylindercoaters. The latter may be used to apply coatings to the back surface ofthe lenticular sheets used in the reflection mode.

FIG. 5 and the perspective view FIG. 11 illustrate the use of a towercoater as a means for producing the thermolens sheet of this invention.Asillustrated in FIGS. 5 and 11, thermosetting resin flows from hopper35 viarollers 36, 37, 38 to the flat surface 49 (shown in FIG. 11) orrecessed patterns 50 (shown in FIG. 11) of cylinder 41 and is thentransferred to the substrate 34 at the cylinder nip 42 where the twocylinders meet. The polymer is formed at the nip 42 of pattern plate 50and substrate 34 underthe pressure of cylinder 43. The polymer is thencured with UV lamp 40 within cylinder 41. The polymer may be furthercured using auxiliary UV lamps 44. Chain drives 45 and 46 deliver thesheet to and from the coater.As shown in FIG. 11, a temperature control"chiller" 55 is used to control the temperature and hence the viscosityof the polymer resin. Chiller 55 is placed between the polymer reserve54 and the pump 56 that provides a metered flow of polymer resin totrough 35. The overflow is returned to temperature control unit 55.

FIG. 6a is a perspective drawing of copper sleeve 109 mounted oncylinder 108. The circumference of cylinder 108 is equal to the lengthof the imagearea. The width of cylinder 108 is equal to the width of thelenticular surface. Copper sleeve 109 is formed by plating cylinder 108with "0" grain copper having adequate thickness for surfacing andtooling to a depth of 0.5 mils to 3 mils.

A lathe (e.g., a computer manipulation controlled lathe) using a concavediamond tip tool 110 having the desired inner radius cuts the lenticularpattern into copper sleeve 109 mounted on cylinder 108 at the requiredline pitch 92. The inner radius of the concave diamond tip tool 110matches the radius of the cylindrical lenticules. After it ishard-plated and polished, copper sleeve 109 is cut through its thickness90 to retrieve a flat matrix 93 from which a polymer "mother"reproduction 94 can be made. This replication becomes relief pattern 22used on the web press of FIG. 4 (shown in perspective view in FIG. 12)or on cylinder 4 ofFIG. 5 (shown in perspective view in FIG. 11).

FIG. 6b shows how a "mother" pattern 94 can be used in place of a reliefpattern formed into the glass cylinder. The "mother" pattern is thenwrapped around the glass cylinder and clamped into position. Motherpattern 94 is formed by impressing a master copper relief pattern 93into a polymer layer bonded to a polycarbonate base film 91. This methodprovides an inexpensive, easy change of the lenticular pattern to matcha given position of image layout. If a "mother" pattern is used as therelief surface 22, it must be protected from the uncured polymer 20 bytheuse of a silicone liquid or wetting agent 28 applied to the reliefsurface 22 by rollers 29 and 30, as shown in FIG. 4.

The use of a CMC lathe on a copper cylinder to create the originallenticulation pattern is not the only method for making the reliefpattern. Other methods for making this pattern may be used, such asstereolithography or Erasable Optical Data Bump-Forming.

Optical Data Bump forming is described in U.S. Pat. Nos. 4,719,615;4,852,075; 4,912,696; 4,780,867; 4,901,304; 4,825,430; and 4,896,314.The optical recording medium in these patents is a unique polymericbump-forming medium. Bumps are recorded on the surface of the polymerfilmusing a laser operating in the visible or near-infrared. It iscapable of forming marks as small as 0.3 μm in diameter. The marks canbe erased bit-by-bit using a laser of a second wavelength, or in sectorsby heating the surface of the coating with an infrared source such asxenon flash lamp. The medium is produced by spin-coating dyed polymerlayers onto a rigid substrate such as a polycarbonate disk, or byweb-coating of the layers onto a flexible substrate such as PET. It canalso be applied to coating rolls, drums or other rigid three-dimensionalsubstrates.

There are two ways in which the optical recording medium can be used in3D imaging. The first is in the production of lenticular screenmaterials. Current methods rely on metal dies which must be machined andthen inserted into a mold for rigid lenticular screens or attached to adrum for flexible screens. Because of the small dimensions of theindividual lenticles (often 32 lines/inch or smaller), machining costsare significant, and the cost of producing large screens (greater than10×14 inches) makes large-scale reproduction and distributionprohibitively expensive. For flexible lenticular products, the situationis slightly better, but the cost of producing and mounting the masterontothe machine is still a significant set-up expense.

The surface topography required for forming lenticles of nearly anydimension can be produced on the optical recording medium quickly andinexpensively using a laser operating under computer control. The energyrequired for exposure is considerably less than that for laser milling,soa relatively low-cost system can be used. For this operation theoptical recording medium could be coated as a flat sheet on a rigidsubstrate (forinsertion into a mold) or as a coating on a cylindricaldrum. The flat sheet would be exposed to produce the required surfacetopography, then inserted into the mold. An acrylic sheet covered with athin layer of photopolymer would be laminated to the master, thenexposed through the acrylic to a UV light source. The photopolymer filmin contact with the master would crosslink to form a negativereproduction of the master. The sheets would then be delaminated and themaster would be reused.

For flexible lenticular materials, a drum coated with the opticalrecordingmedium layers would be mounted onto the printing line after thefinal printstation. The surface topography required would be produced byexposing the drum either on the press or just before mounting. Thiswould replace the machining process presently required to produce amaster. The drum would be continuously coated with a thin layer ofphotopolymer which would conform to the surface of the drum. As thephotopolymer was laminated to the print, it would be exposed to UV lightto form a permanent lens on thesurface of the print. If changes wererequired, either in the registration of the master with the print, or inthe line spacing of the lenticular screen, the drum could be erased andre-exposed on the press. This would allow for rapid changes in printsize and corrections for enlargement effects.

The second way in which the optical recording medium could be used is inthe production and reproduction of holographic images. Because theopticalrecording medium forms surface marks with dimensions comparableto the wavelength of light, it could be used to replace dichromatedgelatin in the production of holographic images. In addition, theoptical recording medium could be used as a master for duplication ofembossed holograms. Itcould be coated onto a drum and exposed to producethe desired image. A polyester sheet coated with a thin photopolymerfilm would then be laminated to the drum and exposed through thesubstrate to UV light. This would polymerize the coating, which wouldthen be pulled off the drum continuously and wound up. The polyesterfilm with the polymerized photopolymer coating would then be metallizedand the resulting images cutout and mounted as required. This wouldgreatly reduce the tooling costs inproducing embossed holograms, sincethe image could be recorded on the drumwith a laser, then erased withoutremoving the drum from the coating machine. A separate master would nolonger have to be machined for each print.

The optical recording medium is well-suited for both these imagingapplications. It can be fabricated in large uniform sheets, then exposedto produce a wide range of surface topographies. It can be producedinexpensively, especially if visible dyes and lasers are used in imageproduction. Since it can be erased, it can be reused readily, making itsuitable for short-run production. Because of these characteristics, ithas the potential to open up new areas of three-dimensional imaging.

FIG. 7a is a perspective drawing of a second preferred embodiment of thepresent invention, which uses a common lithographic offset pressretrofitted with a flowable catalytic resin in trough 97. The resin flowis metered to a raised surface plate 98 wrapped around plate cylinder99. The resin fills the cavities of the relief pattern 100 which iswrapped around the blanket cylinder 101. Cylinder 101 transfers theresin to substrate 104 at predetermined positions 105 and 106. Therelief pattern is in registration with in-line printed complementaryimages 102 from prior press units. It is cured at the nip of cylinders101 and 103 by a bank of UV lamps 107 extending the full width of thesheet. Unlike the first embodiment of FIGS. 4 and 5, there is no UV lampinside the cylinder.

FIG. 7b shows relief plate 94 forming the pattern of cured polymer 95whichis bonded at substrate 96 to produce the lenticular sheets.Substrate 104 may also be continuous length roll material, e.g., when aweb printing press is utilized.

FIG. 8 is a schematic representation of the process of the presentinvention, as shown in the embodiment of FIG. 7a, for making lenticularsheets using paper or opaque substrates and catalytic polymer chemistry.In this embodiment, the UV lamp is outside the cylinder having thelenticular relief pattern. Each process step in FIG. 8 is denoted by astep number 68-73. The process starts at step 68 where three-dimensionalimages are printed onto a substrate. The images can be made as fullcolor lithographic separation films using any of a number ofconventional methods. For example, three-dimensional images can beobtained by direct photography using a special three-dimensional camera.

Such cameras generally have a motorized film back with a barrier stripor lenticulated overlaid mask that is driven the width of a singlelenticule during the full left to right movement of the film back. Asmall aperture or slit at the rear of the lens is synchronized with theother elements toproduce a continuum of perspective images within asingle lenticule at a prescribed pitch determined by the maskingelement. Negatives are generally exposed from still-life compositionsand contact-printed to a positive transparency. The transparency can beused as the master for separation, or duplicated for mounting to acomparable mask (i.e., barrierstrip or lenticular grid) for viewing.

An alternative method is discontinuous photography. Discontinuousphotography uses conventional cameras to expose a number of individualimages at different perspectives with left to right movement of thecamera, or an array of cameras mounted in alignment with synchronizedshutters so that all exposures are made simultaneously. In some cases, amotion picture camera is traversed from left to right on a motor-drivenrail to photograph the discontinuous individual frames, thus producingthedifferent perspectives required for autostereography.

All discontinuous photography methods require the images to besuperimposedinto a single lenticulated transparency by use of acombining device that imposes each frame adjacent to the next withineach lenticule width at thedesired pitch. These photo-mechanicalcombined image masters can be used with barrier-strips or lenticularscreens. These are then mounted to theirrespective barrier strips orlenticular screens having the same pitch, witha slight correction forviewing parallax. The master photo-combined lenticulated film is alsoused as input for the making of lithographic separations.

Discontinuous photography can also be scanned and digitized forcombinationon a computer by interlacing the images for direct output atselected pitchon a graphic arts scanner output device. This process isdescribed in U.S. Pat. No. 5,113,213.

Once the separations and lithographic plates are made conventionalmethods are used to print the image on paper as shown in FIG. 8 at step68. Depending on the type of sheet used, a binder coating of an aqueousacrylic may be used to size the sheet, and prepare the surface to acceptthe thermosetting resin.

After the sheet is coated with the polymer resin, the patterned reliefmolding surface is pressed onto the polymer resin coating. The polymerresin completely fills the cavities in the molding surface under theapplied pressure, while maintaining the desired coating thickness. Theresin is then exposed at the nip of the cylinder to a curing agent(i.e., UV lamps) to cure and harden the resin. The resin retains itsshape and bonds to the precoats of uncured resin as shown at step 71.Additional UV curing may be provided at step 72. The finished product isstacked at step

FIG. 9 is a schematic representation of a process for making lenticularsheets according to the present invention using transparent plasticsubstrates. The clear polycarbonate or polyethylene substrate sheet isless than 20 mils thick. A three-dimensional image is printed on theback side of the sheet in four color process inks.

As in any lithographed product designed for backlighting, the secondimpression increases the image saturation to retain the brilliance ofthe image at high light levels. In order for the sheet to be translucentrather than transparent, one or two impressions of white are appliedover the process colors to act as a diffuser in step 74, or as areflective surface 16 (as shown in FIG. 3).

The substrate may require a paper tip-sheet to obtain proper feed andcontrol.

If a tip-sheet is used, it would have to be removed as the sheet isinverted for processing of the lenticular layer on the opposite side ofthe sheet at step 75. With the thickness of the plastic sheet making upmuch of the lenticule's focal length, only a thin layer of thermosettingpolymer is needed. This layer can be applied to the overall sheet oronly in the image areas by spot coating, as previously explained, atstep 76. As described above with respect to FIG. 8, the relief moldingsurface withthe lenticular design is then pressed against the uncuredresin and cured with UV lamps at step 77. Additional curing may beprovided by auxiliary UV lamps at step 78.

FIG. 10 is a schematic representation of a process for making lenticularsheets according to the present invention using a web press and paper orplastic substrates. If dimensional images are printed on the back sideof a transparent substrate as shown in step 80, the ink can be driedin-line by UV or IR lamps. A base coat can be applied to the oppositeside, if needed, as shown in step 81. UV polymer is added and cured by aUV lamp within a transparent cylinder at step 82 as previously describedin the detailed description of FIG. 4. The web can then be slit andtrimmed to sheet size at step 83 and delivered as finished product atstep 84.

The thermosetting resin suitable for use in forming the transparentouter layer of the lenticular screen is a reactive polymer capable ofbeing polymerized by UV radiation, and a reactive monomer which servesas a diluent for the reactive polymer and facilitates control overviscosity. Viscosity can also be controlled by temperature. The typicaltemperature range of the polymer is 50° to 90° F. Additionally, theresin may include a cure initiator, dyes, pigments and conventionaladditives such as gloss, leveling, flow or wetting agents and adhesionpromoters. The radiation source may be directed through the moldingsubstrate in contact with the resin in the case of clear plastic sheetsbut must be directed to the top surface of the resin and as close to thecylinder nip as possible when using paper.

Examples of reactive polymers suitable for use in radiation curableresin systems include acrylic based polymers derived from epoxies,urethanes, polyesters, and polyethers. The preferred type of reactivepolymer for usein this invention is an acrylated urethane polyesteroligomer, such a UVITHANE 893, an aliphatic diisocyanate based urethaneoligomer having a molecular weight of about 1300. This oligomer is aproduct of the Morton International, Inc. Chemical Division, Woodstock,Ill.

The reactive diluent monomer preferably comprises one or more reactivemono-, di-or-poly-functional acrylic monomers, examples of which includepentaerythritol triacrylate, tri-methylolpropane triacrylate, hexanedioldiacrylate, tetraethylene glycol diacrylate, isobornyl acrylate. Theacrylate monomers serve as a solvent for the reactive polymer and areadded to the polymer in varying amounts to obtain a formulation with thedesired viscosity for obtaining the particular coating thicknessdesired. However, unlike conventional solvents, these monomers becomechemically incorporated into the coating layer by polymerization.

The press polymerization process may be applied to other sorts ofoptical elements useful in three-dimensional and multi-imaging printing.For example, rectangular or cylindrical arrays of lenslets may beimprinted byusing an appropriately constructed impression cylinder.

The lenticular screens produced according to the present invention areunique because the image and the lenticular screen, whether the image isprinted on a paper substrate or on a plastic substrate, are fused into asingle unit. The polymer bonds to the substrate by U.V. radiation.

The foregoing disclosure of embodiments of the present invention hasbeen presented for purposes of illustration and description. It is notintendedto be exhaustive or to limit the invention to the precise formsdisclosed. Many variations and modifications of the embodimentsdescribed herein willbe obvious to one of ordinary skill in the art inlight of the above disclosure. The scope of the invention is to bedefined only by the claimsappended hereto, and by their equivalents.

What is claimed is:
 1. A method of manufacturing autostereogramscomprising:(a) providing a flexible substrate sheet having astereographic image printed thereon; (b) wrapping the flexible substratesheet partially around a transparent cylinder having a relief pattern,said relief pattern being an array of inverse lenticules, said printedstereographic image being aligned in precise registration with the arrayof inverse lenticules; (c) flowing a layer of thermosetting polymerresin between the flexible substrate sheet and the relief pattern on thecylinder, thus impressing an array of lenticules onto the layer ofthermosetting polymer resin; (d) curing the layer of thermosettingpolymer resin with ultraviolet radiation, said radiation emanating froma source within said cylinder; and (e) separating the cured layer ofpolymer resin, having the array of lenticles impressed therein, from thecylinder.
 2. The method of manufacturing autostereograms of claim 1,wherein the relief pattern is an array of inverse cylindricallenticules.
 3. The method of manufacturing autostereograms of claim 2,wherein optical data bump forming techniques are used to manufacture thecylinder having the relief pattern of inverse cylindrical lenticules. 4.The method of manufacturing autostereograms of claim 1, wherein therelief pattern is a transparent mother relief pattern, said transparentmother relief pattern having been formed by impressing a master reliefpattern in a layer of transparent polymer, and the mother relief patternis wrapped around a transparent cylinder to provide the transparentcylinder having the relief pattern of inverse lenticules.
 5. The methodof manufacturing autostereograms of claim 1, wherein the relief patternis a transparent mother relief pattern, said transparent mother reliefpattern having been formed using optical data bump forming techniques.6. The method of manufacturing autostereograms of claim 1, wherein thethermosetting polymer resin is applied to the relief pattern on thetransparent cylinder using a tower coater.
 7. The method ofmanufacturing autostereograms of claim 6, wherein the relief pattern isa transparent mother relief pattern, said mother relief pattern havingbeen formed by impressing a master relief pattern in a layer oftransparent polymer, and the mother relief pattern is wrapped around atransparent cylinder to provide the transparent cylinder having therelief pattern of inverse lenticules.
 8. The method of manufacturingautostereograms of claim 6, wherein the relief pattern is a transparentmother relief pattern, said transparent mother relief pattern havingbeen formed using optical data bump forming techniques.
 9. A method ofmanufacturing autostereograms comprising:(a) providing a transparentcylinder having a relief pattern on its outer surface, said reliefpattern being a lenticular relief pattern comprising an array of inverselenticules, and said transparent cylinder having a source of ultravioletradiation within the transparent cylinder; (b) wrapping a flexiblesubstrate sheet partially around the transparent cylinder, said flexiblesubstrate sheet having a stereographic image thereon, the image being inregistration with the lenticular relief pattern on the transparentcylinder; (c) flowing a thermosetting polymer resin onto the transparentcylinder between the relief pattern and the flexible substrate sheet;(d) curing the thermosetting polymer resin in situ, and simultaneouslybonding the polymer resin to the flexible substrate sheet whilemaintaining the registration between the flexible substrate sheet andthe stereographic image, with ultraviolet radiation produced by thesource of ultraviolet radiation within the transparent cylinder thusproducing a composite lenticular sheet having an array of lenticules onits front surface and a stereographic image; and (e) removing thecomposite lenticular sheet.
 10. The method of manufacturingautostereograms of claim 9, wherein the relief pattern is an array ofinverse cylindrical lenticules.
 11. The method of manufacturingautostereograms of claim 10, wherein optical data bump formingtechniques are used to manufacture the cylinder having the reliefpattern of inverse cylindrical lenticules.
 12. The method ofmanufacturing autostereograms of claim 10, wherein the relief pattern isa transparent mother relief pattern, said transparent mother reliefpattern having been formed by impressing a master relief pattern in alayer of transparent polymer, and the mother relief pattern is wrappedaround a transparent cylinder to provide the transparent cylinder havingthe relief pattern of inverse lenticules.
 13. The method ofmanufacturing autostereograms of claim 9, wherein the relief pattern isa mother relief pattern, said mother relief pattern having been formedusing optical data bump forming techniques.
 14. The method ofmanufacturing autostereograms of claim 9, wherein the thermosettingpolymer resin is applied to the relief pattern on the cylinder using atower coater.
 15. An apparatus for fabricating lenticular sheetautostereograms comprising:(a) computer means for combining planarimages of an object into a combined image, each of the planar imagesbeing a view of the object from one of a plurality of differentviewpoints; (b) printer means for printing the combined image onto aflexible substrate; (c) a transparent cylinder comprising a lenticularrelief pattern on its outer surface, said lenticular relief patterncomprising an array of inverse lenticules; (d) means for wrapping saidflexible substrate partially around said transparent cylinder such thatthe combined image is in registration with the lenticular reliefpattern; (e) means for providing a metered flow of ultraviolet-curablethermosetting polymer resin onto the lenticular relief pattern anddepositing a layer of polymer resin between the lenticular reliefpattern and the flexible substrate; (f) means for controlling thethickness of the layer of polymer resin; and (g) means for producingultraviolet radiation, said means being positioned within saidtransparent cylinder such that at least some of the ultravioletradiation is incident upon the thermosetting polymer resin, theultraviolet radiation having the characteristics necessary for curingand hardening the polymer layer and bonding the polymer layer to theflexible substrate such that the combined image remains in registrationwith the lenticular pattern.
 16. The apparatus for fabricatingautostereograms of claim 15, wherein the relief pattern is an array ofinverse cylindrical lenticules.
 17. The apparatus for fabricatingautostereograms of claim 16, wherein optical data bump formingtechniques are used to manufacture the cylinder having the reliefpattern of inverse cylindrical lenticules.
 18. The apparatus forfabricating autostereograms of claim 15, wherein the relief pattern is atransparent mother relief pattern, said transparent mother reliefpattern having been formed by impressing a master relief pattern in alayer of transparent polymer, and the mother relief pattern is wrappedaround a transparent cylinder to provide the transparent cylinder havingthe relief pattern of inverse lenticules.
 19. The apparatus forfabricating autostereograms of claim 15, wherein the relief pattern is amother relief pattern, said mother relief pattern having been formedusing optical data bump forming techniques.
 20. The apparatus forfabricating autostereograms of claim 15, wherein the thermosettingpolymer resin is applied to the relief pattern on the cylinder using atower coater.
 21. An apparatus for fabricating lenticular sheetautostereograms comprising:(a) a transparent cylinder having alenticular relief pattern on its outer surface, said lenticular reliefpattern comprising an array of inverse lenticules; (b) means within thetransparent cylinder for producing ultraviolet radiation; (c) means forwrapping a flexible substrate having a stereographic image thereonpartially around said transparent cylinder such that the stereographicimage is in registration with the lenticular relief pattern; (d) meansfor providing a metered flow of ultraviolet-curable thermosettingpolymer resin onto the lenticular relief pattern and depositing a layerof polymer resin between the lenticular relief pattern and the flexiblesubstrate; (e) means for controlling the thickness of the layer ofpolymer resin; (f) means for directing the ultraviolet radiation at thelayer of polymer resin such that the ultraviolet radiation cures andhardens the layer of polymer resin and bonds the flexible substrate tothe layer of polymer resin such that the stereographic image remains inregistration with the lenticular pattern, thus producing a compositelenticular sheet; and (g) means for separating the composite lenticularsheet from the transparent cylinder.
 22. The apparatus for fabricatingautostereograms of claim 21, wherein the relief pattern is an array ofinverse cylindrical lenticules.
 23. The apparatus for fabricatingautostereograms of claim 22, wherein optical data bump formingtechniques are used to manufacture the cylinder having the reliefpattern of inverse cylindrical lenticules.
 24. The apparatus forfabricating autostereograms of claim 21, wherein the relief pattern is atransparent mother relief pattern, said transparent mother reliefpattern having been formed by impressing a master relief pattern in alayer of transparent polymer, and the mother relief pattern is wrappedaround a transparent cylinder to provide the transparent cylinder havingthe relief pattern of inverse lenticules.
 25. The apparatus forfabricating autostereograms of claim 21, wherein the relief pattern is amother relief pattern, said mother relief pattern having been formedusing optical data bump forming techniques.
 26. The apparatus forfabricating autostereograms of claim 21, wherein the thermosettingpolymer resin is applied to the relief pattern on the cylinder using atower coater.
 27. An apparatus for fabricating lenticular sheetautostereograms comprising:(a) printer means for printing anautostereographic image onto a flexible substrate; (b) a transparentcylinder comprising a lenticular relief pattern on its outer surface,said lenticular relief pattern comprising an array of inverselenticules; (c) means for wrapping said flexible substrate partiallyaround said transparent cylinder such that the autostereographic imageis in registration with the lenticular relief pattern; (d) means forproviding a metered flow of ultraviolet-curable thermosetting polymerresin onto the lenticular relief pattern and depositing a layer ofpolymer resin between the lenticular relief pattern and the flexiblesubstrate; (e) means for controlling the thickness of the layer ofpolymer resin; and (f) means for producing ultraviolet radiation, saidmeans being positioned within said transparent cylinder such that atleast some of the ultraviolet radiation is incident upon thethermosetting polymer resin, the ultraviolet radiation having thecharacteristics necessary for curing and hardening the polymer layer andbonding the polymer layer to the flexible substrate such that theautostereographic image remains in registration with the lenticularpattern.
 28. The apparatus for fabricating autostereograms of claim 27,wherein the relief pattern is an array of inverse cylindricallenticules.
 29. The apparatus for fabricating autostereograms of claim28, wherein optical data bump forming techniques are used to manufacturethe transparent cylinder having the relief pattern of inversecylindrical lenticules.
 30. The apparatus for fabricatingautostereograms of claim 27, wherein the relief pattern is a transparentmother relief pattern, said transparent mother relief pattern havingbeen formed by impressing a master relief pattern in a layer oftransparent polymer, and the transparent mother relief pattern iswrapped around a cylinder to provide the transparent cylinder having therelief pattern of inverse lenticules.
 31. The apparatus for fabricatingautostereograms of claim 27, wherein the relief pattern is a motherrelief pattern, said mother relief pattern having been formed usingoptical data bump forming techniques.
 32. The apparatus for fabricatingautostereograms of claim 27, wherein the thermosetting polymer resin isapplied to the relief pattern on the cylinder using a tower coater. 33.The apparatus of claim 32, wherein the relief pattern is an array ofinverse cylindrical lenticules.
 34. The apparatus of claim 22, whereinthe relief pattern is a transparent mother relief pattern, saidtransparent mother relief pattern having been formed by impressing amaster relief pattern in a layer of transparent polymer, and thetransparent mother relief pattern is wrapped around a cylinder toprovide the transparent cylinder having the relief pattern of inverselenticules.